Potato Leafhopper Management in Alfalfa - University of Nebraska
Biology and Management of Lygus in...
Transcript of Biology and Management of Lygus in...
Integrated Pest Management of Lygus in Alfalfa Seed Production
Ricardo Ramirez
Utah State University
Department of Biology
Integrated Pest Management (IPM)
• IPM is the use of multiple pest management strategies and the judicious use of pesticides to prevent, reduce, or eliminate pests.
IPMPROGRAM
IDENTIFICATION
PREVENTION
MONITORING
MULTIPLE TACTICS
Lygus bug identification
• Belongs to the Mirid family of true bugs.
• Lygus bugs are small (5 mm; 0.18 inch) with piercing-sucking mouthparts. Variation of green to brown color.
• Wings folded over the abdomen with a distinct scutellum (triangle area) with heart shape behind the head.
Adult Lygus
Lygus bug identification
• Be aware of look-alikes.
• Aphids are very small, soft bodied, with piercing-sucking mouthparts. Look similar to early stage Lygus. Lygus move quickly compared to aphids.
• Alfalfa plant bugs are also Mirids. Thinner and twice the size of Lygus (3/8 inch). Legs have speckled black spots.
Aphids Alfalfa plant bug
Lygus bug biology
• Overwinter as adults. Movement to overwintering sites in the fall.
• Sites include plants crowns, litter, debris, field margins, natural areas.
• Become active and mate in spring.
Adult Lygus
Lygus bug biology
• Eggs deposited in plant tissue. Hatch within 1-4 wks
• Nymphs have 5 instars (immature stages) developing in 1-2 months.
• Have 3-4 overlapping generations per year (SW Idaho).
Lygus bug feeding
• Piercing-sucking mouthparts
• Prefer reproductive plant parts (buds, flowers, seeds)
• Reproductive stage alfalfa vs nearly any other plant
ALFALFA WINS
Lygus bug feeding
• Very broad host range
• Ornamental perennials (penstemon and lupine)
• Weeds (Russian thistle, kochia, mustards)
Lygus bug damage
• Results in Physical Damage from probing.
• Inject salivary enzymes into plant tissue.
• Results in Chemical Damage.• Deformed growth• Death of plant tissue
Lygus bug damage
• Cause blasting (drying) of flower buds.
• Leads to flower, seed pod shedding.
• A component of reduced seed numbers.
Lygus bug damage
• Most damage results from feeding on immature seeds in developing pods.
• Upwards of 70% of damage caused by late instars (4-5) and adults.
• Damage occurs with the green seed since they can’t penetrate hard seed.
• Left unmanaged, losses can reach 50% to nearly 100%.
Integrated Pest Management (IPM)
• IPM is the use of multiple pest management strategies and the judicious use of pesticides to prevent, reduce, or eliminate pests.
IPMPROGRAM
IDENTIFICATION
PREVENTION
MONITORING
MULTIPLE TACTICS
Lygus prevention
• Management of weeds
• Management of overwintering sites
Integrated Pest Management (IPM)
• IPM is the use of multiple pest management strategies and the judicious use of pesticides to prevent, reduce, or eliminate pests.
IPMPROGRAM
IDENTIFICATION
PREVENTION
MONITORING
MULTIPLE TACTICS
Lygus bug management
• Monitoring• Sweep sampling
Plant stage # Lygus/Sweep Strategy
Prior to bloom and pollinator release
>4 Lygus Active management
During bloom toseed set
8-10 Lygus Active management
Alfalfa seed set and maturing
10-15 Lygus Active management
NO YES
Lygus bug management
• Monitoring• Sweep sampling
Plant stage # Lygus/Sweep Strategy
Prior to bloom and pollinator release
>4 Lygus Active management
During bloom toseed set
8-10 Lygus Active management
Alfalfa seed set and maturing
10-15 Lygus Active management
NO YES
Integrated Pest Management (IPM)
• IPM is the use of multiple pest management strategies and the judicious use of pesticides to prevent, reduce, or eliminate pests.
IPMPROGRAM
IDENTIFICATION
PREVENTION
MONITORING
MULTIPLE TACTICS
Lygus bug management
• Chemical control• PRE-Bloom: Organophosphates and Pyrethroids
Lygus bug management
• Chemical control• Reduced efficacy because of Lygus resistance issues
Pesticide Resistance may be defined as ‘a genetically based (heritable) decrease in susceptibility to a pesticide in a population’.
Driving Pesticide Resistance
First Generation
Susceptible
Resistant
Driving Pesticide Resistance
Later Generations
Susceptible
Resistant
Lygus bug management
• Chemical control• Reduced efficacy because of Lygus resistance issues
• Need for chemical rotations
Group 1: Acetylcholinesterase inhibitors1A Carbamates1B Organophosphates
Group 2: GABA-gated chloride channel agonists2A Cyclodiene Organochlorines2B Phenylpyrazoles (Fiproles)
Group 3: Sodium channel modulators3A Pyrethroids/Pyrethrins3B DDT, Methoxychlor
Group 4: Nicotinic acetylcholine receptor agonists4A Neonicotinoids4B Nicotine4C Sulfoxaflor
Lygus bug management
• Bloom period• Options more critical because of insecticide toxicity to pollinators and
beneficials.
Lygus bug management: Trial 1
• Bloom period
Dr. Jim BarbourUniv. of Idaho-Parma
Trial Highlights
• Treatments reduced small and large Lygus nymphs.
• Transform-BeLeaf-Rimon provided best suppression
• BeLeaf-Transform-Warrior rotation least suppression
• No major impact on Lygus predators from any rotation treatment
Lygus bug management: Trial 2
Trial Highlights
• Treatments reduced small and large Lygus nymphs.
• 2 applications better than 1 for both low and high rates.
• Transform (2 applications) provided equal or better suppression than 2 applications of BeLeaf or Warrior.
Trial Highlights: Beneficials
• Transform (1 application) did not reduce predator numbers.
• BeLeaf treatments (1 or 2 applications) did not reduce predator numbers.
• Two applications of all other insecticides reduced predator numbers.
• Transform at 2.25 oz/acre likely could be applied late evenings, or early mornings without a significant hazard to adult ALCB.
Availability of management
• Transform approved in 2013.
• Sulfoxamine insecticide (IRAC group 4C)
• Acts on nicotinic acetylcholine receptors
• Systemically active
• Good activity on sap feeding insects
• Lower activity on most predators and pollinators.
Availability of management
• Transform approved in 2013.
• Transform revoked in 2015.
• Transform emergency use approval denied in 2016 because No data showing that:• Lygus pressure has increased.
• Available products are not effective.
• Economic losses on alfalfa seed yield increased dramatically as a result of Lygus pressure.
Lygus management research
• USDA-NIFA-Alfalfa Forage and Research Program Grant• Developing an attractant for Lygus derived from host plant volatile
compounds.
Zain SyedUniv. of Kentucky
Johanna BrunetUSDA-ARS/Univ. of Wisconsin
Ricardo RamirezUtah State Univ.
Lygus host plants
Goosefoot Shepherd’s purseYellow sweet clover
Queen Anne’s lace (wild carrot)Horseweed
What plant smells are out there?
Identifying the attractant (=bait)
Visit utahpests.usu.edu